Intestinal parasites are Giardia lamblia, Cryptosporidium parvum, Entamoeba histolytica, hookworms, ascaris, tape worms and others. As to organ parasites, their life-threatening courses are pointed out: amebiasis in the intestine, liver, lung and brain, toxoplasmosis in the brain, lung and heart muscle, including the danger for the child of a pregnant woman with an acute infection, West African sleeping sickness with encephalitis, the East African form with polyserositis, South American Chagas' disease with intestinal and myocardial involvement, visceral leishmaniasis Kala Azar, the filariasis Onchocerca volvulus with threatening blindness, the dog tapeworm with cysts and Echinococcus multilocularis with carcinoma-like infiltration of the liver and other organs, cysticercosis of the brain, eye and muscle tissue; partly generalizing parasitoses in immuno-suppressed including AIDS patients, finally skin parasites as causes of disease (e.g. scabies), and as potential carriers of pathogens.